Submitted to: Chicken Genomics and Development Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/2005
Publication Date: 5/8/2005
Citation: Kogut, M.H., He, H., Kaiser, P. 2005. Lipolysaccharide binding protein/CD14/TLR4-dependent recognition of Salmonella-LPS induces the functional activation and up-regulation of pro-inflammatory cytokine and chemokine gene expression in chicken heterophils [abstract]. Chicken Genomics and Development. p. 34.
Technical Abstract: Lipopolysaccharide (LPS) is the major pathogen associated molecular pattern (PAMP) found in the cell wall of gram-negative bacteria and, in mammals, is recognized by the Toll-like receptor 4 (TLR4) in conjunction with the serum protein, lipopolysaccharide-binding protein (LBP), and the CD14 co-receptor. We have found that chicken heterophils constitutively express multiple TLR including TLR4. Interestingly, ultra-pure LPS from Salmonella minnesota directly induced the functional activation of heterophils without the presence of LBP. However, the role of LBP and CD14 in the recognition of LPS and the induction of functional activation and innate cytokine and chemokine gene expression in chicken heterophils is not known. As previously seen, in the absence of chicken serum, heterophil exposure to the ultra-pure LPS stimulated an increased degranulation response. However, the presence of 5% chicken serum (the presumptive source of LBP) in the culture medium increased heterophil degranulation by 84%. In addition, the presence of either soluble recombinant human LBP (68%) or CD14 (39%) also up-regulated the heterophil degranulation response. Incubation of heterophils with either chicken serum or rhLBP also significantly induced the up-regulation of pro-inflammatory cytokines (IL-1beta, IL-6, and IL-18) and chemokines (IL-8, K60, MIP1beta, and the CXC receptor 1) mRNA expression. Moreover, polyclonal antibodies directed to rat CD14 and human TLR4, but not TLR2, blocked the LPS-mediated degranulation and the up-regulation of the proinflammatory cytokines and chemokines. These data clearly demonstrate that LBP and CD14/TLR4 engagement is directly involved in LPS-mediated functional activation and innate immune gene expression in chicken heterophils.